This is a study of infant feeding practices among Arab Bedouins residing in the Negev, Israel. The objectives are: infant feeding practices at birth and changes during the first year of life and relationships to physical growth and to gastrointestinal and respiratory morbidity during the first 18 months of age. The data base includes information on 5,000 mother-infant pairs, and represents the total population of Bedouin births during the years 1981 and 1982. Two subsamples have been identified for followup; one at birth and followed for a period of 5-8 months. Another sample of children was identified at 6 months of age and followed prospectively to 18 months of age. Several manuscripts have been published which include: undernutrition among Bedouin Arab infants, seasonality of births among Bedouin Arabs, the 40 day rest period and infant feeding practices and perinatal factors influencing infant feeding practices at birth. Three additional manuscripts are in press.